Acetylcholinesterase activity in rat thymus after immunostimulation with interleukin beta

The occurrence and distribution of Acetyl, cholinesterase (AChE) activity w ere examined in the thymus of normal and immune-stimulated adult and aged r ats using biochemical and enzymhistochemical methods. Specific AChE reactiv ity was found primarily in the arteries and, to a lesser extent, in the vei ns. Only a small amount of activity could be observed in association with t he subcapsular and medullary part of the parenchyma and nerve fibers. Our f indings indicate that AChE activity in the rat thymus increases after treat ment with interleukin beta. In fact treatment with interleukin beta induces an increase of protein cont ent, of the amounts of AChE biochemically assayed and at the levels of AChE histoenzymatically stained. Furthermore, staining of the different structu res of the thymus in treated or untreated rats shows that the significant m odifications concern the parenchyma, the structures resembling nerve fibers and the whole thymus, while only small changes are observed in AChE activi ty located in the walls of arteries, veins and lymphatic vessels.